Analysis of the saliva proteome from patients with head and neck squamous cell carcinoma reveals differences in abundance levels of proteins associated with tumour progression and metastasis.

The objective of this study was to identify differentially expressed proteins in saliva from HNSCC patients compared to a control group. Saliva samples from eight individuals with non-malignant conditions of the head and neck region were employed as a control group and compared to saliva from eight patients with HNSCC using 2D DIGE analysis and subsequent mass spectrometry identification of candidate proteins. Beta fibrin (+2.77-fold), S100 calcium binding protein (+5.35-fold), transferrin (+3.37-fold), immunoglobulin heavy chain constant region gamma (+3.28) and cofilin-1 (+6.42) were all found to be significantly increased in the saliva from HNSCC samples compared to the control group whereas transthyretin (-2.92-fold) was significantly decreased. The increased abundance of one of the proteins identified (S100 calcium binding protein) was confirmed by immunoblot analysis. Many of these proteins are involved in tumour progression, metastasis and angiogenesis. The proximity of saliva to the developing tumour is undoubtedly a major factor in facilitating detection of these proteins and such a strategy may lead to the development of a panel of biomarkers useful for therapeutic monitoring and for early detection of HNSCC.